This application has been constructed to provide a focused effort designed to produce new drugs to treat patients infected with Pneumocystis carinii, Toxoplasma gondii, or cytomegalovirus infections. The groups include synthetic organic chemists whose goal will be to synthesize new candidate compounds with the aim of identifying agents of greater potency as well as selectivity, biological scientists who will seek to isolate and characterize key enzymes of P. carinii and T. gondii and who will also evaluate the new synthetic compounds for their efficacy against T. gondii both in vitro and in vivo, and virologists who will seek to identify new agents effective against cytomegalovirus in a screening program on selected compounds provided by Du Pont, our industrial partner. Compounds from the synthesis program will also be evaluated against P. carinii in programs at Indiana University sponsored by NIAID.